Monica Dell'Acqua

MediaChrom: Discovering a Class of Pyrimidoindolone-Based Polarity-Sensitive Dyes.

A small library of six polarity-sensitive fluorescent dyes, nicknamed MediaChrom, was prepared. This class of dyes is characterized by a pyrimidoindolone core fitted out with a conjugated push-pull system and a carboxy linker for a conceivable coupling with biomolecules. The optimized eight-step synthetic strategy involves a highly chemo- and regioselective gold-catalyzed cycloisomerization reaction. The photophysical properties of MediaChrom dyes have been evaluated in-depth. In particular, the MediaChrom bearing a diethylamino as an electron-donating group and a trifluoromethyl as an electron-withdrawing group displays the most interesting and advantageous spectroscopic features (e.g., absorption and emission in the visible range and a good quantum yield). Promising results in terms of sensitivity have been obtained in vitro on this dye as a membrane/lipophilic probe and as a peptide fluorescent label.

Synthesis of two unnatural oxygenated aaptaminoids.

Two unprecedented oxygenated aaptaminoids have been synthesized starting from cheap and easily available 2,3-dihydroxybenzoic acid with the satisfactory overall yields of 31% and 34%. The key step of the procedure is the divergent thermic 5-exodig vs base-promoted 6-endodig cyclization of a 5-alkynylquinolinone derivative.

Silver comes into play: Henry reaction and domino cycloisomerisation sequence catalysed by [Ag(I)(Pc-L)] complexes

We report herein the synthesis of new pyridine-containing macrocyclic ligands (Pc-L) bearing a non-innocent pendant arm, by exploiting both chiral and functional properties of natural amino acids. The obtained macrocyclic ligands were employed to synthesize well-defined cationic silver(I) complexes that were shown to be competent catalysts for the Henry (nitroaldol) reaction. Good to excellent yields and full selectivity in the β-nitroalcohol product were obtained starting from electron-poor aromatic aldehydes or other activated aldehydes such as furfural under mild reaction conditions. The straightforward synthesis of the macrocyclic ligands starting from cheap commercially available starting materials allowed the introduction of a suitable basic functionality into the ligand pendant arm, thus providing a bifunctional catalyst. Based on our previous experience in the [Ag(I)(Pc-L)] catalysed domino addition/cycloisomerisation reaction of o-alkynylbenzaldehydes and nucleophiles, the synthesis of isochromenes coupling the Henry reaction and the cycloisomerisation in a single step was subsequently explored. Although with low selectivity, [Ag(I)(Pc-L)] cationic complexes were able to promote such a cascade reaction and a possible mechanism based on experimental evidence has been proposed.